1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer which is provided with a detachable photosensitive drum cartridge.
2. Description of the Related Art
In a related art image forming apparatus such as a copying machine or a laser beam printer, as shown in FIGS. 18 to 20, a photosensitive drum cartridge 2 is mounted detachably in the main body 1 of the apparatus, and a photosensitive drum is detachably supported by the main body 3 of the cartridge.
An assembling member 4 for fixing to the apparatus main body 1 is mounted to the cartridge main body 3. As shown in FIG. 18, the assembling member 4 comprises a flexible handle portion 5, and an assembling portion 6 which supports the handle portion 5 and is screwed to the cartridge main body 3.
The handle portion 5 has a substantially V-like shape consisting of a fixed handle piece 7 fixed to the assembling portion 6, and a movable handle piece 9 which is swingably connected to the fixed handle piece 7 through a resilient U-like rib 8.
As shown in FIG. 19, at the center of the outer side wall of the movable handle piece 9, formed is an engaging claw 12 which is to engage with an engaging hole 11. The engaging hole 11 is formed at the upper portion of a guide groove 10 formed in the apparatus main body 1. Therefore, when the handle portion 5 of the assembling member 4 is pressed into the guide groove 10 as shown in FIG. 20, the engaging claw 12 engages with the engaging hole 11, thereby positioning the photosensitive drum cartridge 2 in the vertical direction.
When the photosensitive drum cartridge 2 is removed from the apparatus main body 1, the movable handle piece 9 is pressed toward the fixed handle piece 7 so that the engaging claw 12 is disengaged from the engaging hole 11, thereby performing the removal of the cartridge.
The assembling member 4 further comprises a finger insertion hole 13 and a screw insertion hole 14, and the cartridge main body 3 comprises a boss 15 which is to be guided through the guide groove 10 so that the photosensitive drum cartridge 2 is correctly positioned with respect to the apparatus main body 1.
In the photosensitive drum cartridge 2 in the prior art, the cartridge main body 3 requires members such as shafts and bearings for rotatably supporting the photosensitive drum, and fastening parts such as screws for fixing these members to the cartridge main body 3, resulting in the increased number of parts. This causes the step of assembling the photosensitive drum cartridge 2 to be cumbersome, thereby increasing the cost.
The positioning of the photosensitive drum cartridge 2 in the vertical direction with respect to the apparatus main body 1 is effected by the engagement of the engaging claw 12 of the assembling member 4 and the engaging hole 11 of the apparatus main body 1. However, the constitution for positioning the photosensitive drum cartridge 2 in the horizontal direction is not sufficiently considered, with the result that the photosensitive drum cartridge 2 is liable to be dislocated in the horizontal direction.